At unaware

from The Collaborative International Dictionary of English v.0.48

Unawares \Un`a*wares"\, adv.
   Without design or preparation; suddenly; without
   premeditation, unexpectedly. "Mercies lighting unawares."
   --J. H. Newman.
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         Lest unawares we lose
         This our high place, our sanctuary, our hill. --Milton.
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   {At unaware}, or {At unawares}, unexpectedly; by surprise.
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            He breaks at unawares upon our walks. --Dryden.
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            So we met
            In this old sleepy town at unaware.   --R. Browning.
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